Given the military's penchant for secrecy, and its tight grip on Ms. Suu Kyi, both meetings are remarkable for having occurred. Senator Webb also secured the release of John Yettaw, a former US veteran who had been jailed until Sunday for swimming across a lake to Suu Kyi's villa in May. The hard-line junta is seeking to portray these as significant concessions, but it's too early to tell whether they will be a catalyst for talks aimed at easing US sanctions in exchange for real democratic reform and proof that Burma (Myanmar) is not pursuing nuclear weapons.

"To meet Suu Kyi and Than Shwe is a critical moment," says Pavin Chachavalpongpun, a research fellow at Singapore's Institute of Southeast Asian Studies. "We could even see some major change. The fact is, the US is now trying to be nice. The world's only superpower came down to Naypyidaw [Burma's capital]. Even [United Nations Secretary-General] Ban Ki-moon wasn't given a chance to meet Suu Kyi. But to secure John Yettaw is not a miracle. This man is no one."

Did Webb make progress?

If Webb, who says he did not go to Burma as an official envoy of the Obama administration, made great progress in pushing for democratic reforms in return for an easing of US sanctions during either sit-down, he is so far refusing to claim it.

In his talks with Than Shwe, heavy US sanctions against Burma were not discussed, "though obviously it's the elephant in the bedroom," Webb told reporters in Bangkok. They also failed to discuss Burma's rumored nuclear ambitions, even though the threat was singled out by Secretary of State Hillary Rodham Clinton at a summit last month in Thailand.

Webb also has yet to share the junta's reaction to his request for Suu Kyi's release, a key goal of his trip. "I think we'll wait and see how their government reacts to this request," he said. "That's probably where we should leave it right now."

Webb's only tangible prize from the Burma trip was the release of Mr. Yettaw.

The junta is thought to have released Yettaw, an epileptic whose condition deteriorated in confinement, simply so he wouldn't die on their watch. His uninvited visit to Suu Kyi's home, a violation of Suu Kyi's house arrest, the junta claimed – extended her detainment by 18 months.

This will effectively muzzle Suu Kyi as the junta gears up for 2010 elections, a move cynics believe will lead to a military-backed government with only the veneer of democratic legitimacy.

Why did Webb go?

Webb, head of the Senate's Foreign Relations subcommittee on East Asia and Pacific affairs, has ties to Southeast Asia tracing back to his Marine Corps days seizing bunkers during the Vietnam War. He speaks Vietnamese, returns to the region frequently, and previously toured Burma in 2001.

That trip drove him to declare the failure of US sanctions, which include bans on American investment and all exports to the US. Still, US leaders such as Mrs. Clinton have shown reluctance to lift the bans until Suu Kyi is freed.

Would Suu Kyi back an easing of US sanctions?

However, if Suu Kyi herself encourages lifting sanctions, as Webb suggested, that could change. "It was my clear impression," he said, "that she is not opposed to lifting some sanctions."

In May, Suu Kyi said Burma still had "many opportunities for national reconciliation if all parties concerned are really willing to achieve," according to her political party in exile, the National League for Democracy. "It is not still too late to have good results out of this misfortune."

Burmese exiles split on US role

Burma's pro-democracy diaspora is split on whether the US should take a softer or harder line with the junta. The junta's track record is grisly, with human rights groups accusing the military of forced labor and gang rape against ethnic minorities as a sanctioned military tactic.

"There's a rational voice among Burmese exiles that wants engagement with the junta," says Aung Zaw, a Burmese exile and editor of The Irrawaddy, a Thailand-based journal of Burmese affairs. "But it's only wishful thinking that the junta will change because of the US."

The junta is kept afloat through trade with China, India, Russia, and Thailand. High-ranking officials, including Clinton, have also warned of military-secret sharing with North Korea and the possibility of a nuclear Burma.

Beijing has refrained from outright censure of Suu Kyi's detainment and announced, after her most recent sentencing, that outsiders should respect Burma's sovereignty. But Western powers could push China to demand better behavior from the junta, Mr. Thitinan says, a tactic Suu Kyi's own lawyer has promoted.

"The cards are overwhelmingly stacked against [Suu Kyi]," Thitinan says. "We have to conclude that the playing field will ultimately be uneven. But just how uneven the field is could still be worked out."